In a recent, brief interview with YouTube tech reviewer Marques Brownlee, billionaire-philanthropist Bill Gates talked about his views on electric vehicles such as Tesla, as well as his thoughts on emissions from the transportation sector. In the short conversation, the Microsoft co-founder praised Tesla’s electric cars, though he also admitted that there is still a lot that needs to be done to make transportation significantly cleaner.

Bill Gates is no stranger to Tesla’s vehicles. Back in 2016, the tech titan was filmed driving casually in a Tesla Model X with Seveneves author Neal Stephenson. Referring to the Silicon Valley-based electric car maker in his recent interview; Gates pointed out that Tesla’s vehicles are “amazing,” while stating that the company still has a long road ahead. The Microsoft co-founder also noted that car buyers would soon have more electric vehicles to choose from.

“Tesla is an amazing product that’s catching on, but it’s still a pretty small percentage of the market. It’s a premium price vehicle, and they lost their $7,500 tax credit, so it’s making it tougher. Now, a ton of other manufacturers are gonna come in, partly because the California zero emissions and partly because people see these trends. There will be a lot of great electric cars to choose from,” Gates said.

Unfortunately, Bill Gates still appeared to be quite cautious with the idea of batteries being used for the long-haul market. The billionaire-philanthropist further added that electric cars would not be fully emissions-free until the grid becomes completely independent of fossil fuels.

“(For) passenger cars — the power output you need is lower than for a truck. So eventually, batteries might work for a truck, but it’s a far more difficult problem because the weight is a lot higher there. Even those passenger cars, one thing to be careful of is unless the electric has gotten to zero, the electric car is still an emitter because of the indirect emissions from the electricity it uses. And so, only in the places where you both get the electric cars to a high percentage and you get the electric sources to be zero emissions, then you’ve got that passenger transport car piece near to zero,” Gates said.

While the Microsoft co-founder has a valid point regarding his concerns about electric vehicles, it should be noted that EVs are cleaner than fossil fuel-powered cars even if the electricity used to charge them comes mainly from coal. This point was highlighted in a recent study from Bloomberg NEF, which concluded that carbon dioxide emissions from battery-powered vehicles are 40% lower than those from cars equipped with internal combustion engines, even in areas that are reliant on coal such as China.

The billionaire-philanthropist also appears to be discounting the progress in battery technology that have been accomplished by companies such as Tesla. Over the past year, Elon Musk hinted that Tesla is already closing in on the $100 per kWh mark, which would help the company’s electric cars achieve price parity with gas-powered vehicles. Battery tech has also progressed to a point where the Tesla Semi, an upcoming all-electric long-hauler, has been noted to feature closer to 600 miles per charge. So compelling are the improvements in batteries that even companies such as Nikola Motor, which has sworn by hydrogen-electric tech, have decided to release battery-powered variants of its upcoming trucks.

Based on Bill Gates’ statements in his interview with Marques Brownlee, it appears that it would still take some time before he fully warms up to the idea of battery-powered vehicles serving as potential catalysts for the world’s transition towards sustainable energy. Considering Tesla’s progress over the years, it might only be a matter of time before the Microsoft co-founder fully embraces electric cars.